The present invention relates to a solid which does not self-igniting, comprising:
a) at least one support component,
b) at least one chemical compound which per se is self-igniting,
c) at least one inert liquid and
d) further components if desired.
The present invention additionally relates to processes for preparing a solid which does not self-ignite and to the use of such a solid for catalytic or stoichiometric carbon-carbon bond linking or for hydrogenation.
It has long been known, and is frequently desirable, to fix reactive, chemical compounds chemically or physically on support materials and thereby to enhance their suitability for particular chemical processes. Examples of important industrial-scale chemical processes are polymerization, hydrogenation or the drying of fluids, for example liquids or gases.
In polymerization processes, for example, especially in the production of polyolefins, use is made of solid, support-bound Ziegler, Phillips or metallocene catalyst systems. A common feature of these catalysts is that they include generally pyrophoric constituents, with the result that the catalysts may spontaneously ignite, especially under oxidizing conditions, for example on the ingress of air.
The self-ignitability of the solids, demonstrated by way of example in polyolefin catalysts, hinders or even prevents totally their use in large-scale industrial processes, since for safe working it necessitates special protective measures, which are often expensive and technically complex.
In addition, the classification of these solids, especially the polyolefin catalysts, as self-igniting substances greatly limits their transportation; for example, rapid despatch by air freight is not permitted.
WO 95/07939, WO 87/03889, WO 93/23439 and WO 94/28034 disclose the preparation of support-bound metallocene catalysts in suspension, subsequent removal of the solvent and drying of the solid to give a free-flowing catalyst. WO 93/23439 specifies drying as an essential step to obtain catalysts having advantageous properites. The dried catalysts of the prior art have the disadvantage that they are self-igniting.
Wetting of the dry solids, especially the polymerization catalysts, leads in general to unwanted properties in the catalysts, such as reduced polymerization activity, or formation of lumps which are difficult to meter.
It is an object of the present invention, therefore, to provide solids, especially flowable polyolefin catalysts, which are not self-igniting and which are virtually unimpaired in their other relevant properties.
We have found that this object is achieved by a solid which does not self-ignite, comprising:
a) at least one support component,
b) at least one chemical compound which per se is self-igniting,
c) at least one inert liquid and
d) further components if desired.
This solid is referred to below as xe2x80x9cnovel solidxe2x80x9d. We have also found a process for preparing a novel solid where the components a) to d) are mixed and then some of component c) is removed. We have also found a process for preparing a novel solid where components a) to d) are mixed, then virtually all of component c) is removed, and then a component c) is added to the dry solid again in an amount such that this solid does not self-ignite. We have also found that the novel solid can be used for catalytic or stoichiometric carbon-carbon bond linkage or for hydrogenation or drying of liquids.
There is broad scope for variation in the support component a). All organic or inorganic solids are suitable in general, especially those that are porous. Examples of particularly suitable inorganic support components a) are particulate oxides or salts. Examples of particularly suitable organic support components a) are particulate polymers.
Examples of particulate organic support material a) are polyolefins such as polyethylene, polypropylene, poly-1-butene and polymethyl-1-pentene and copolymers with the monomers on which these polymers are based, and also polyesters, polyamides, polyvinyl chloride, polyacrylates, polymethacrylates and polystyrene. However, preference is given to particulate inorganic support materials a), such as porous oxides, for example SiO2, Al2O3, MgO, ZrO2, TiO2, B2O3, CaO and ZnO. Metal halides, such as MgCl2, are other suitable supports. The support materials a) preferably have a particle diameter of from 1 to 300 xcexcm, in particular from 30 to 70 xcexcm. Examples of particularly preferred supports are silica gels, preferably those of the formula SiO2.aAl2O3, in which a is a number in the range from 0 to 2, preferably from 0 to 0.5; ie. aluminosilicates or silicon dioxide. Products of this kind are obtainable commercially, for example Silica Gel 332 from Grace.
There is likewise broad scope for variations in the component b) which per se is self-igniting and is defined by its property of self-ignition. Self-ignition is defined by the UN Recommendations Section 14.3 and EEC Directive 92/69, A 13, as described at length in the Examples. Examples of compounds which fall within this definition are organometallic compounds, metal hydrides or organometal hydrides, principally those of groups 1, 2, 3, 4, 5, 6, 12, 123, 13, 14 and 15 of the Periodic Table of the Elements (group numbering in accordance with the 1985 IUPAC Recommendation). Examples of particularly suitable components b) are lithium organyls, aluminum organyls and boron organyls. Preference is given to open-chain or cyclic alumoxane compounds which according to U.S. Pat. No. 4,794,096 can be obtained by reacting aluminum trialkyls with water. They are composed of from 5 to 30 structural units "Brketopenst"O Al(R1)"Brketclosest" connected in chain form or cyclic form, in which each R1 is a C1-C4-alkyl, preferably methyl or ethyl. The alumoxane compounds can also be present in a mixture with other metal alkyls, preferably with aluminum alkyls.
Also used are aluminum organyls of the formula Al(Rxe2x80x2)3, in which Rxe2x80x2 is hydrogen, C1-C10-alkyl, preferably C1-C4-alkyl, especially methyl, ethyl or butyl. Rxe2x80x2 can also be arylalkyl or alkylaryl each of 1 to 10 carbons in the alkyl and 6 to 20 carbons in the aryl. Also suitable are aluminum alkyls Al(Rxe2x80x2)3 in which Rxe2x80x2 can be fluorine, chlorine, bromine or iodine, with the proviso that at least one radical Rxe2x80x2 is a C-organic radical or hydrogen. Particularly preferred compounds are trimethylaluminum, triethylaluminum, triisobutylaluminum, diisobutylaluminum hydride and diethylaluminum chloride.
The components b) can be employed alone or as mixtures in the novel solid, the proportions of the mixture not being critical.
The components b) are generally applied by impregnating the support solid with the liquid and/or dissolved components b). Solvents suitable for this purpose are in general those which constitute component c). Component c) is an inert liquid, in other words a chemical compound which is liquid under standard conditions and which under standard conditions does not undergo, or undergoes only very slowly, chemical reaction with component b), with partial or complete chemical conversion of component b), in general decomposition, or with its own partial or complete chemical conversion. Partial chemical conversion is generally not the case until more than about 10 mol-%, preferably 3 mol-% and, in particular, 1 mol-% of the pure substance c) employed has been converted.
Highly suitable compounds for use as component c) are inert organic compounds such as aliphatic, isocyclic or aromatic hydrocarbon carbons. Examples are n-hexane, n-heptane, n-octane, isododecane, cyclohexane, toluene, ethylbenzene, 1-hexene, 1-pentene, 1-heptene and 1-octene, preferably n-heptane. It is of course also possible to use mixtures or isomers of these compounds as component c), especially those which are offered commercially, such as EC 180 from Shell or Isopar from Exxon.
The content of the liquid c) in the novel solid comprising a) to c) and optionally d) is such that c) is just no longer self-igniting but is still flowable, ie. contains virtually no coarse components. In accordance with our current state of knowledge, the amount of the liquid c) depends inter alia on the propensity to self-ignition of component b).
The novel solid usually comprises from 10 to 70% by weight, based on the solid not containing c), of c), preferably from 25 to 60% by weight and, in particular, from 30 to 40% by weight of c), as determined by the method of gas chromatography.
Polymerization catalysts, preferably olefin polymerization catalysts, based on the novel solid normally comprise a transition metal component d) as well.
Examples of particularly suitable transition metal components d) are the halides, preferably the chlorides, or alkoxides, preferably methoxides, ethoxides or isopropoxides, of the transition metals titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten. Very particularly preferred components d) are metallocene complexes, ie. transition metal compounds having at least one cyclopentadienyl ligand or at least one ligand derived from the cyclopentadienyl structural unit.
Particularly suitable metallocene complexes are those of the formula I 
where
M is titanium, zirconium, hafnium, vanadium, niobium or tantalum,
X is fluorine, chlorine, bromine, iodine, hydrogen, C1-C10-alkyl, C6-C15-aryl, alkylaryl having 1 to 10 carbons in the alkyl and 6 to 20 carbons in the aryl, xe2x80x94OR7 or xe2x80x94NR7R8, where
R7 and R8 are C1-C10-alkyl, C6-C15-aryl, alkylaryl, arylalkyl, fluoroalkyl or fluoroaryl each of 1 to 10 carbons in the alkyl and 6 to 20 carbons in the aryl,
R2 to R6 are hydrogen, C1-C10-alkyl, 5- to 7-membered cycloalkyl which in turn may carry a C1-C10-alkyl as substituent, C6-C15-aryl or arylalkyl, where two adjacent radicals may together be saturated or unsaturated cyclic groups of 4 to 15 carbons, or are Si(R9)3 where
R9 is C1-C10-alkyl, C3-C10-cycloalkyl or C6-C15-aryl, 
Z is X or
xe2x80x83where
R10 to R14 are hydrogen, C1-C10-alkyl, 5- to 7-membered cycloalkyl which may in turn carry a C1-C10-alkyl as substituent, C6-C15-aryl or arylalkyl and where two adjacent radicals together may be saturated or unsaturated cyclic groups of 4 to 15 carbons, or are Si(R15)3 where
R15 is C1-C10-alkyl, C6-C15-aryl or C3-C10-cycloalkyl, or where the radicals R5 and Z together form a group xe2x80x94R16xe2x80x94Axe2x80x94in which 
R16 is
xe2x80x83xe2x95x90BR17, xe2x95x90AlR17, xe2x80x94Gexe2x80x94, xe2x80x94Snxe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x95x90SO, xe2x95x90SO2, xe2x95x90NR17, xe2x95x90CO, xe2x95x90PR17 or xe2x95x90P(O)R17,
xe2x80x83where
R17, R18 and R19 are identical or different and are hydrogen, halogen, C1-C10-alkyl, C1-C10-fluoroalkyl, C6-C10-fluoroaryl, C6-C10-aryl, C1-C10-alkoxy, C2-C10-alkenyl, C7-C40-arylalkyl, C8-C40-arylalkenyl or C7-C40-alkylaryl or where two adjacent radicals in each case with the atoms linking them form a ring, and
M2 is silicon, germanium or tin,
A 
xe2x80x83where
R20 is C1-C10-alkyl, C6-C15-aryl, C3-C10-cycloalkyl, alkylaryl or Si(R21)3,
R21 is hydrogen, C1-C10-alkyl, C6-C15-aryl which may in turn be substituted by C1-C4-alkyl, or is C3-C10-cycloalkyl
or where the radicals R5 and R13 together form a group xe2x80x94R16xe2x80x94. of the metallocene complexes in formula I, preference is given to 
Preference is given to those transition metal complexes which contain as ligands two, possibly bridged, aromatic ring systems, ie. in particular the transition metal complexes of the formulae Ib and Ic.
The radicals X can be identical or different but are preferably identical.
Of the compounds of the formula Ia, particular preference is given to those where
M is titanium, zirconium or hafnium,
X is chlorine, C1-C4-alkyl or phenyl, and
R2 to R6 are hydrogen or C1-C4-alkyl.
Of the compounds of the formula Ib, in those which are preferred
M is titanium, zirconium or hafnium,
X is chlorine, C1-C4-alkyl or phenyl,
R2 to R6 are hydrogen, C1-C4-alkyl or Si(R9)3 and
R10 to R14 are hydrogen, C1-C4-alkyl or Si(R15)3.
Particularly suitable compounds are those of the formula Ib in which the cyclopentadienyl radicals are identical.
Examples of particularly suitable compounds include:
bis(cyclopentadienyl)zirconium dichloride,
bis(pentamethylcyclopentadienyl)zirconium dichloride,
bis(methylcyclopentadienyl)zirconium dichloride,
bis(ethylcyclopentadienyl)zirconium dichloride,
bis(n-butylcyclopentadienyl)zirconium dichloride and
bis(trimethylsilylcyclopentadienyl)zirconium dichloride
and also the corresponding dimethylzirconium compounds.
Of the compounds of the formula Ic, particular suitability is possessed by those where
R2 and R10 are identical and are hydrogen or C1-C10-alkyl,
R6 and R14 are identical and are hydrogen, methyl, ethyl, isopropyl or tert-butyl,
R3, R4, R11 and R12 are defined as follows:
R4 and R12 are C1-C4-alkyl,
R3 and R11 are hydrogen,
or two adjacent radicals R3 and R4 and R11 and R12 together are cyclic groups of 4 to 12 carbons,
R16 is 
M is titanium, zirconium or hafnium and
X is chlorine, C1-C4-alkyl or phenyl.
Examples of particularly suitable complex compounds include
dimethylsilanediylbis(cyclopentadienyl)zirconium dichloride,
dimethylsilanediylbis(indenyl)zirconium dichloride,
dimethylsilanediylbis(tetrahydroindenyl)zirconium dichloride,
ethylenebis(cyclopentadienyl)zirconium dichloride,
ethylenebis(indenyl)zirconium dichloride,
ethylenebis(tetrahydroindenyl)zirconium dichloride,
tetramethylethylene-9-fluorenylcyclopentadienylzirconium dichloride,
dimethylsilanediylbis(3-tert-butyl-5-methylcyclopentadienyl)-zironium dichloride,
dimethylsilanediylbis(3-tert-butyl-5-ethylcyclopentadienyl)-zirconium dichloride,
dimethylsilanediylbis(2-methylindenyl)zirconium dichloride,
dimethylsilanediylbis(2-isopropylindenyl)zirconium dichloride,
dimethylsilanediylbis(2-tert-butylindenyl)zirconium dichloride,
diethylsilanediylbis(2-methylindenyl)zirconium dibromide,
dimethylsilanediylbis(3-methyl-5-methylcyclopentadienyl)-zirconium dichloride,
dimethylsilanediylbis(3-ethyl-5-isopropylcyclopentadienyl)-zirconium dichloride,
dimethylsilanediylbis(2-methylindenyl)zirconium dichloride,
dimethylsilanediylbis(2-methylbenzindenyl)zirconium dichloride
dimethylsilanediylbis(2-ethylbenzindenyl)zirconium dichloride,
methylphenylsilanediylbis(2-ethylbenzindenyl)zirconium dichloride,
methylphenylsilanediylbis(2-methylbenzindenyl)zirconium dichloride,
diphenylsilanediylbis(2-methylbenzindenyl)zirconium dichloride,
diphenylsilanediylbis(2-ethylbenzindenyl)zirconium dichloride,
and dimethylsilanediylbis(2-methylindenyl)hafnium dichloride
and also the corresponding dimethylzirconium compounds.
Of the compounds of the formula Id, those which are to be mentioned as being particularly suitable are those where
M is titanium or zirconium,
X is chlorine, C1-C4-alkyl or phenyl,
R16 is 
A is 
xe2x80x83and
R2 to R4 and R6 are hydrogen, C1-C10-alkyl, C3-C10-cycloalkyl, C6-C15-aryl or Si(R9)3, or where two adjacent radicals are cyclic groups of 4 to 12 carbons.
Complex compounds of this kind can be synthesized by methods known per se, with preference being given to the reaction of the appropriately substituted, cyclic hydrocarbon anions with halides of titanium, zirconium, hafnium, vanadium, niobium or tantalum.
Examples of corresponding preparation techniques are described, inter alia, in the Journal of organometallic Chemistry, 369 (1989), 359-370.
It is also possible to employ mixtures of different metallocene complexes.
The novel solid, and especially the polymerization catalysts based on it, may additionally include, as component d), a compound which forms metallocenium ions. This can be selected either from the group of the compounds b), preferably aluminoxanes and especially methylaluminoxane, or from the group of the following compounds, if desired in addition to b).
Suitable compounds which form metallocenium ions are strong, neutral Lewis acids, ionic compounds with Lewis-acid cations, and ionic compounds with Brxc3x6nsted acids as cation.
Preferred strong, neutral Lewis acids are compounds of the formula II
M3X1X2X3xe2x80x83xe2x80x83II
where
M3 is an element from main group III of the Periodic Table, especially B, Al, Ga preferably B, and
X1, X2 and X3 are hydrogen, C1- to C10-alkyl, C6- to C15-aryl, alkylaryl, arylalkyl, haloalkyl or haloaryl each having 1 to 10 carbons in the alkyl and 6 to 20 carbons in the aryl, or are fluorine, chlorine, bromine or iodine, and in particular are haloaryls, preferably pentafluorophenyl.
Particularly preferred compounds of the formula II are those in which X1, X2 and X3 are identical, preference being given to tris(pentafluorophenyl)borane.
Suitable ionic compounds with Lewis-acid cations are compounds of the formula III
[(Ya+)Q1Q2 . . . Qz]d+xe2x80x83xe2x80x83III
where
Y is an element from main groups I to VI or from subgroups I to VIII of the Periodic Table,
Q1 to Qz are radicals with a single negative charge such as C1-C28-alkyl, C6-C15-aryl, alkylaryl, arylalkyl, haloalkyl or haloaryl each of 6 to 20 carbons in the aryl and 1 to 28 carbons in the alkyl, or are C1-C10-cycloalkyl which may be substituted by C1-C10-alkyls, or are halogen, C1-C28-alkoxy, C6-C15-aryloxy, silyl or mercaptyl groups,
a is an integer from 1 to 6,
z is an integer from 0 to 5, and
d corresponds to the difference a-z but is greater than or equal to 1.
Carbonium cations, oxonium cations, and sulfonium cations, and cationic transition metal complexes, are particularly suitable. Particular mention may be made of the triphenylmethyl cation, the silver cation and the 1,1xe2x80x2-dimethylferrocenyl cation. They preferably possess noncoordinating counterions, especially boron compounds as are specified in WO 91/09882, preferably tetrakis (pentafluorophenyl) borate.
Ionic compounds with Brxc3x6nsted acids as cations and preferably likewise noncoordinating counterions are specified in WO 91/09882; a preferred cation is N,N-dimethylanilinium.
Suitable processes for preparing the novel solid are the following.
Support solid a), preferably a porous inorganic oxide, especially silica gel, is suspended in the inert liquid c), preferably an aliphatic, isocyclic or aromatic hydrocarbon, especially heptane and/or toluene. The component b), preferably an organometallic compound from group 3 of the Periodic Table of the Elements or an aluminoxane, as defined above, preferably methylaluminoxane, or else a mixture of components b) and d), which may also react chemically with one another, is added to the suspension. Components b) and, if desired, d) can also be present as solutions, preferably in inert organic solvents, such as aliphatic, isocyclic hydrocarbons or aromatic hydrocarbons, ie. n-hexane, n-heptane, isododecane, toluene or ethylbenzene. The temperatures for this reaction are not critical. Components a), b) and c) and, if used, d) are usually reacted at from xe2x88x9270 to 120xc2x0 C., preferably at from 0 to 50xc2x0 C.
Subsequently, virtually all of the solvent c) can be removed and the solid which remains is dried, usually at from 20 to 120xc2x0 C., and a defined amount of component c) is added (variant A), or else the amount of component c) in the novel solid can be established at the desired level by incomplete removal (variant B). The liquid c) added in variant A can, but need not, be chemically identical to the liquid c) originally present in the mixture.
A highly suitable process for preparing a solid polymerization catalyst, preferably for olefin polymerization, which is not self-igniting is the following.
Support solid a), preferably a porous inorganic oxide, especially silica gel, is suspended in the inert liquid c), preferably an aliphatic, isocyclic or aromatic hydrocarbon, especially heptane and/or toluene. Component b), preferably an organometallic compound from group 3 of the Periodic Table of the Elements, such as tri-C1-C10-alkylaluminum compounds, especially trimethylaluminum, or an aluminoxane, as defined above, preferably methylaluminoxane, is added to the suspension. Component b) can also be present as a solution, preferably in inert organic solvents, such as aliphatic, isocyclic hydrocarbons or aromatic hydrocarbons, ie. n-hexane, n-heptane, isododecane, toluene or ethylbenzene. The temperatures for this reaction are not critical. Components a), b) and c) are usually reacted at from xe2x88x9270 to 120xc2x0 C., preferably from 0 to 50xc2x0 C. After this impregnation process, it is common to remove virtually all of the solvent and to dry any solid which remains, preferably at from 20 to 120xc2x0 C., in particular at from 40 to 80xc2x0 C. The drying period is generally not critical and as a rule is in the range from 0.1 to 24 hours, depending on batch size.
The solid obtainable in this way is then usually mixed with a solution of the metallocene, preferably of the biscyclopentadienyl compounds Ib, Ic as defined above, especially bis(n-butylcyclopentadienyl)zirconium dichloride, bis(isobutylcyclopentadienyl)zirconium dichloride, dimethylsilanediylbis(indenyl)zirconium dichloride, dimethylsilanediylbis(2-methylbenzoinindenyl)zirconium dichloride, and with the metallocenium-forming compound, preferably methylaluminoxane. Subsequently, the solvent c) is normally removed almost completely, the solid which remains is dried, preferably at from 20 to 120xc2x0 C., in particular from 40 to 80xc2x0 C., and a defined amount of component c) is added (variant A) or else the amount of component c) in the novel solid can be established at the desired level by incomplete removal of component c) (variant B). The liquid c) added in variant A can, but need not, be chemically identical to the liquid c) originally present in the mixture.
The solid catalysts obtainable in this way are highly suitable for polymerizing C2-C12-alk-1-enes at from xe2x88x9250 to 300xc2x0 C. under pressures in the range from 0.5 to 5000 bar.
Of the C2-C12-alk-1-enes, preference is given to ethylene, propene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene and to mixtures of these C2-C12-alk-1-enes. Particular preference is given to homo- or copolymers of propene, the proportion of propene in the copolymers being at least 50 mol-%. Of the propene copolymers, those which are preferred include ethylene or 1-butene or mixtures thereof as additional monomers. Preferred ethylene polymers are copolymers with a proportion of from 50 to 99.9 mol-% of ethylene and from 0.1 to 50 mol-% of a C3-C10-alk-1-ene such as propene, 1-butene, 1-hexene, 1-octene, 1-decene or a mixture of these C3-C10-alk-1-enes, the proportions in the mixture not being critical.
The process for preparing polymers is usually conducted at from xe2x88x9250 to 300xc2x0 C., preferably at from 0 to 150xc2x0 C., and at pressures in the range from 0.5 to 5000 bar, preferably from 1 to 80 bar.
The polymerization can be accomplished in solution, in suspension, in liquid monomers or in the gas phase. Polymerization is preferably effected in liquid monomers, in suspension or in the gas phase, preference being given to the stirred gas phase or to the gas-phase fluidized-bed technique.
The process can be carried out continuously or batchwise. Suitable reactors include continuously operated stirred vessels or fluidized-bed reactors; alternatively, if desired, a row of series-connected reactors (reactor cascade) can be used.
The novel solid is notable for its lack of self-ignitability, which has been defined in accordance with the UN Recommendations Section 14.3 and EEC Directive 92/69, A 13. In accordance with these recommendations, the storage of small amounts of the novel solid in air is investigated. If it has not self-ignited within five minutes, it is classified as not self-igniting.
The novel solid, preferably consisting of components a), b) and c), can be used to dry fluids. Examples of these fluids are monomers, such as the above-defined C2-C2-12-alk-1-enes, for example ethylene, propylene, 1-butene and 1-hexene, and also organic solvents, such as those which constitute component c), examples being n-heptane and toluene. Gaseous fluids are the noble gases, preferably argon, and also nitrogen and gaseous hydrocarbons, for example propane and butane.